Load test on three phase squirrel cage induction motor

As the load is increased the rotor speed is slightly reduced. The emf induced in the rotor causes the current increased to produce higher torque, untill the torque developed is equal to torque required by load on motor. Equivalent Circuit of Three Phase Squirrel Cage Induction Motor.

AiTo conduct the No Load test and Blocked rotor on three phase squirrel cage induction Motor.

Fuse Rating calculation: No Load: of rated current ( Full load current).

REGULATION OF ALTERNATOR BY EMF AND MMF METHODS.

Besides the motor, mechanical lo.

A large percentage of the electrical power generated in the world is consumed by induction motors , as these are the main drive motors used in the industries. Practicing engineers should be conversant with the performance characteristics. Thus no load and blocked rotor tests are performed on the motors.

As the name suggest no load test is performed when rotor rotates with synchronous speed and there is no load torque. This test is similar to the open circuit test on transformer. Actually, to achieve synchronous speed in an induction motor is impossible.

One of the wattmeter deflects in negative diretion during no load. Construction of three phase squirrel cage induction motor - Duration: 3:37.

The no load test on an induction motor gives information with respect to exciting current and no-load losses. The test is performed at rated frequency and with balanced poly- phase voltages applied to the stator terminals. Readings are taken at the rated voltage, after the motor runs long enough for the bearings to be properly . No- Load and Blocked Rotor Test on.

To obtain the variation of no load power and current and blocked rotor power and current with changes in the applied voltage to the stator. Constant losses are those losses which are considered to remain constant over normal working range of induction motor. To determine the equivalent circuit parameters of an induction motor.

The fixed losses can be easily obtained by performing no- load test on the three phase induction motor. These losses are further classified as-. Starting torque is the torque produced by induction motor when it is started. We know that at start the rotor spee N is zero.

So, the equation of starting torque is easily obtained by simply putting the value of s = in the equation of torque of the three phase induction motor , The starting torque is also known as standstill torque . The rotor is connected to the mechanical load through the shaft.

The construction of single phase induction motor is almost similar to the squirrel cage three phase motor except that in case of asynchronous motor the stator have two windings instead of . This method of speed control can only be applied for squirrel cage motor. Pole amplitude modulation method (PAM) – In this method of speed control of three phase induction motor the original sinusoidal mmf wave is modulated by another sinusoidal mmf wave having different number of poles. Let f1(θ) be the original mmf . We have to perform no load and blocked rotor test in an induction motor.

In no load test , the induction motor is run at no load and by two watt meter metho its total power consumed is calculated which is composed of no load losses only. From here no load current and the angle between voltage . The air gap in magnetizing branch in an induction motor slowly increases the exciting current and the no load stator I2R loss can be recognized.

KEYWORDS: Induction motor , No load test , Blocked rotor test, Vibration. A typical - phase squirrel - cage motor has six connection leads in the .